Design

Admiral Irosoku Yamamoto recommended the development of a long range medium bomber to support the Imperial Japanese Navy when he was the chief of the Technical Division of the Naval Bureau of Aeronautics in 1933. An 8-Shi specification was given to Mitsubishi. In the mid 1930s the Mitsubishi G3M was developed.

Armament

As the G3M was a navy bomber it could carry a single torpedo under the fuselage.

Prototype

Ka-9

The Ka-9 prototype had two Hiro Type 91 (500 hp) liquid cooled 12 cylinder engines. It could go a maximum of 3,760 miles.

The first Ka-9 prototype was flown in April 1934 by Yoshita Kajima.

Ka-15

The tests of the prototype were very successful and a 9-Shi specification was developed for a bomber that could carry 1,764 lb / 800 kg of bombs and be defended by three 7.7 mm / 0.303" machine guns. This was to become the Ka-15 prototype.

At Kagamigahara in July 1935, Yoshita Kajima and Lieutenant Sada test flew the Ka-15.

Production

Mitsubishi stopped production in 1941 to focus on the G4M. Nakajima continued production until 1943.

Usage

Units

Sino-Japanese War

Starting in 1937 the G3Ms were used in the Sino-Japanese war.

The Japanese Imperial Navy's Kanoya Kokutai, based at Tapei, first used G3M2 Model 21s in raids on Hangchow and Kwangteh in August 1937 / August 14, 1937. As they went over 1,250 miles of open water, this was the first ever trans-ocean bombing raid in history.

On August 15, 1937, the Kisarazu Kokutai, based at Omura, Kyushu, executed a raid on China with G3M2s.

By 1940 there were around 130 G3M2s in four kokutais. By December 1941 there were 204.

As the G3Ms were beyond the range of fighter escorts they did suffer heavy losses.

Around the World

From August 26 to October 20, 1939, a L3Y-2 flew 33,000 miles in 194 hours around the world.

Pacific War

By December 1941 there were approximately 250 G3Ms in service. During the first two years of the Pacific War, the G3M was the main medium bomber of the Imperial Japanese Navy.

HMS Repulse and Prince of Wales

The G3M2s played a major part in the sinking, off of Malaya on December 10, 1941, of the HMS Repulse and Prince of Wales.

Sixty G3M2s of the Genzan and Mihoro Kokutais flew from Indo-China and took part in the attack.

Secondary Roles

After 1942 the G3M was primarily relegated to secondary roles such as transport, training, and glider towing. Some had search radar added and were used as long range maritime patrol bombers.